Allow User Registration

You can allow user registration from Settings → General as displayed in the screen shot below. Mark the membership checkbox and select the appropriate role based on your requirements. You can read more about WordPress Roles and Capabilities to make a better decision. Also, Keep in mind that there are various plugins that you can use to edit WordPress user roles. Make sure to save the changes.

Now, Your website users will be able to sign up as pointed in the screen shot below.